Studies on the properties of the oxidation and reduction of pure cytochrome c with the two segments of the respiratory chain of beef heart mitochondrial membrane are being done. The kinetics of the reaction point to the involvement of different groups on cytochrome c in the oxidation and reduction reactions, and the reactions with well-characterized derivatives of cytochrome c and purified cytochromes from different species are being examined. In addition separation of site-specific antibody populations to cytochrome c is being pursued. Dissection of the cytoplasmic membrane of the aerobic bacterium Micrococcus denitrificans and the elucidation of composition and enzymatic properties of the segments are proceeding. Studies on the distribution of the redox pigments of the respiratory chain system in the cytoplasmic membrane of intact Micrococcus denitrificans are in progress.